1. Field of the Invention
The present invention relates to a clutch actuator. More particularly, the present invention relates to a clutch actuator that changes operation force applied to a clutch by a worm wheel rotated by a motor.
2. Description of Related Art
Generally, a clutch actuator for a manual transmission uses hydraulic pressure to control engaging and releasing of a clutch. A conventional clutch actuator generally includes a clutch disk, a clutch cover, a clutch fork, an operation cylinder, a master cylinder, and a clutch pedal.
A clutch fork engages or releases a clutch cover to a clutch disk by contacting or releasing the cover and disk. The clutch disk and the clutch cover are thus frictionally engaged such that torque applied to the clutch cover is transmitted to the clutch disk. That is, in a case in which the clutch disk and the clutch cover are closely contacted, the torque of the clutch cover is transmitted to the clutch disk by the frictional force. When the clutch disk is separated from the clutch cover, the clutch disk and the clutch cover rotate separately.
The clutch fork closely contacts the clutch cover to the clutch disk or separates the clutch cover from the clutch disk so as to engage or release the clutch. The clutch fork is operated by the operation cylinder. The master cylinder generates hydraulic pressure that is supplied to the operation cylinder and is mounted between the clutch pedal and the operation cylinder. Therefore, when the driver pushes the clutch pedal, the master cylinder generates hydraulic pressure and supplies the hydraulic pressure to the operation cylinder to engage the disk and cover.
Such actuators are used mainly for manual transmissions. However, the use of manual transmissions is decreasing because of control difficulties thereof. On the contrary, use of double clutch transmissions (DCTs) or automated manual transmissions (AMTs) are on the rise. In double clutch and automated manual transmissions, the clutch is controlled by an electrical signal. Therefore, a pressure-operated clutch actuator is difficult to apply in these cases.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.